HDX500 tail not holding

[concept1]

i finally got my HDX 500 Sah flying fairly well, except the tail will not "stay" solid. initially it flies great but sometimes after about 3 minutes into the flight the tail will not hold at all, it drifts all over. I am using the 401 which came from another heli and it is known to be good and using a digital futaba servo, i will have to check which one. and the castle 10 amp bec. my only thoughts are maybe do to vibtations or something is getting hot? I beleive the castle is set for 5v which should not be a problem, but even if it's 6 that should be ok with the 401?
the rest of the setup is stock motor and 6s A123

[Wyldman]

Is it possible that you might be running the gyro gain a tad too close to the threshold? I've been instructed to set the gain value up until the tail starts wagging, then back it off until it settles down. My thinking is that if the gain was already set on the previous bird it might bear checking again, after it warms up it may be running a bit hot, gainwise.

I'm no expert and your mileage may vary....

[concept1]

Yea I backed it back already from the past bird, it holds pretty good for a while, I may back it down a bit more, I also have some vibration but not too bad, I have flown much worst with no problems! it just goes all crazy and almost looses all control

[BigKid]

On mine, the tail rotor shaft had excessive side to side play in the belt pulley. There is a pin that goes through the shaft and keeps the pulley from rotating on the shaft- the shaft and pin will move side-to-side inside the pulley. I filed down the side of the pulley where the pin goes in and then put shims in to take up the play. Check yours. Another symptom is that the heli won't stop immediately after any sudden input. Let me know if this helped.

[concept1]

think I found my problem, I am running the CC Bec and a Gaui esc. they are not compatible! after a few minutes the bec doesn't govern the power properly causing the gyro to go nuts! Guess I need either a new ESC or run a rx pack and a regulator.

[concept1]

Acctually the problem was the plastic tail case! even after I swapped out my BEC, the problem was still their, and I found the tail case had worn the bearing seats so the shaft had some play causing vibs, or cauing the gyro and servo to overwork! I replaced with the metal tail assembly and it flies much better now, much smoother and the tail is rock solid now!